Agricultural and earth-working implements, like tractors, are required to operate under widely varying conditions of load, terrain, soil conditions and speeds. All purpose implements of this type are therefore typically provided with transmissions having many gear ratios or positions, numbering as many as eighteen. In addition, those implements frequently are provided with what is commonly known as a creep clutch.
A creep clutch modifies the normal output of the tractor transmission thereby enabling the tractor to travel at greatly reduced or creeping speeds, but with greater torque. The slower speed and increased torque are desirable and useful under certain operating conditions, such as muddy soil or very heavy towing loads. However, it is necessary for efficient use of the equipment that positive control be exercised over the creep clutch to prevent inadvertent engagement or disengagement under certain conditions. For example, engagement of the creep clutch while the tractor is operating at relatively high speed could result in damage to the tractor transmission or other components of the drive train. Similarly, disengagement of the creep clutch while the tractor is being operated in the upper speed range of the creep mode can result in undesirable lurching of the tractor, again with the potential of damaging the tractor drive train.
There thus exists a need for a creep clutch control that is simple to use and insures against the types of inadvertant engagement or disengagement described.